Variable mica condenses



Aug. 2, 1927. 1, 7, 5

A. W. FRANKLIN VARIABLE MIQA CONDENSER Filed Oct. 11. 1923 any.

ATTORNEY Patented Aug. 2, 1927.

UN'ETED STATES ENT QFFI E- ALBERT W. FRANKLIN, on NEW YoRK, N. Y.,ASSIGNOR ro cans. FRESHMAN co. me, or NEW Yorcx, N. Y., A CORPORATION015' NEW YORK.

VARIABLE MI CA CONDENSER.

Application filed October 11, 1923. Serial No. 667,879.

This invention relates to improvements in that class of apparatus usedfor varying the capacity in an electric circuit, commonly known asvariable condensers.

.One of the objects of the invention is to provide a device for thispurpose that is compact in form, easily assembled and operated, notreadily liable to derangement and which is capable of producing minutevariations between zero and full capacity.

Another purpose is to produce an apparatus having a sealed chambercontaining a liquid conductor and contacting element free from dust,corrosion or coatings ordinarily gathered by exposure to the air,thereby assuring proper and uniform electrical contact and consequentlyattaining a predetermined result in accordance with the position of itsparts.

A further object is to secure intimate contact between the conductorsand the intervening dielectric or insulating material, thus avoidingvariation in capacity resulting from irregularity of the spaces so oftenfound between these elements of condensers of the prior art. Theconductor being liquid, its physical area may change-to vary thecapacity, it contacting readily with and tak iug the form of thecontainer ,or enclosure, in filling interstices and preventing air gaps,

etc. f

A further aim is in the provision of an apparatus of unusual simplicity,well suited for use in connection with the various forms of telephonynow in common vogue.

These and analogous aims and objects are accomplished by the novelconstruction, combination and arrangement of parts hereinafter fullydescribed and illustrated in the accompanying drawing, forming amaterial part of this disclosure, and in which Figure 1 is a partialside elevational, partial sectional view of an embodiment of theinvention as completely assembled.

Figure 2 is a plan view of the dielectric chamber looking from the openinner side.

Figure 3 is a similar view of the chamber cover.

Figure 4 is a vertical transverse sectional view showing a modified formof chamber complete with its mountings, drawn to a. smaller scale.

Figure 5 is an interior plan view of one of the chamber sides.

Figure 6 is a like view of the other side of the chamber.

By further reference to the drawing it will be seen that Fig. 1illustrates a common application ofthe invention, the numeral 10designatin a conventional type of radio base boarc and 11 the frontpanel of the same. i

Fixed on the board 10 is a base plate 12 made of non-conducting materialand secured on its upper surface are two uprights 13 and 14 havingoppositely bent feet 15 and 1 6 clamped to thebase plate by bolts 17 and18; the bolt heads are entered in counterbored openings in the xbottomof the plate d h i bQdit P idfid w th amp u 19 and 20 above which. a rethumb nuts 21 an 22eoes u ipgfiin c mbinati t b a omm n pe of bind P Theupperends of the uprights are bored n ter, t e upri h 1. rotatablypper-t g a 2 2 4 ma ing upright W 5 i: m un ed n i a spi d e .4.,extending Hawaiian peninaintbdimp at 11 n in st? it exten in @ndris aknu n b 25 he breast ever 26e s orm wi h bstsll s ie -27, whichi qy-be gad t 3 l .-9 ll i 9Q:W h' r 'P QV-Q m rk .Q&$l Q-W ,1.tbe-ia eiof hment-'1 Th St m te a -wv th a s ud 28 aving a thln disc-likegheadigfland a, single radial plate-like ;extension 30.;."' I

A cipcular member ,3-1 o f dielectric material, ,a s .or sinilapsubstance of the Q LD g oup, is moulded. concentrically on the disc 29and plate 30st -;t. ha t their ree s ir inn e -are fiush an level,firmly cu n th 'pa -t h ni The member 31 has, .ai-raised.. peripheral ea2 and i rment seat i i3,-' il s he ght sas im in a ren w-c mbe 3 ofnlive a h except f r an emeat a ep esr vhi'sh ts a reserv rt a q antityof mercury 36 therein.

The mercury may be entered when the member is held level, and sealed bya mica plate 37 held on the seat 33 by a suitable adhesive and clampedby the raised element 38 of a disc 39 made of similar material as themember 31, fitted to the ring 32 and held this space however beingslightly above the level of the mercury in the reservoir 35 in themating element.

The disc 39 is moulded on the thin, enlarged head 42of acylindrical'extension 43 '1 of the spindle 24, said extension 43 andstud 28 having distinct shoulders abutting the inner faces of theuprights 13 and14 to prevent end motion of the device.

It willnow be apparent that upon turning the knob and graduated disc 27integral with it,'th spindle 24 will convey rotary motion to-the disc39, which motion is transmitted by the screws 40 to the chambered member31, stud 28an'd stem 23. 3

"It will also be obvious that as the chambered plateis rotated, eversolittle, that the mercury in the reservoir 35 will flow out into'thespace 34, making co'ntact with the plate 3Q, and covering a'portion ofthe mica plate 3", and when the condenser is in an elec tricalcii'cuitcausing an induced current to pass through'the-plate in'extent dependingon the amount of rotation-imparted, the. mercury also making adirectelect rical contact with the disc 29gand arm 7303 T If connectedin electrical circuit by the binding posts l7 and'=18,- with" themercury 36 at the lowest pointl'in' tlie"reservoir 35, there will nocapacity fie'ct, therebe ing no conductor opposite the reservoir and thedial should register Zero capacity. YT f rotated 1S0 tlie'maximumcapacity is'freached, the-mercury having run outof 'its rese'rvoir bygravity into' the"'chamber' lgt forming a thin sheet Whose 'are'a'is'qlalzit leastto the area of the opposed conductor 36f. -=j

In the modification shown in F 1', 5 and6 a quite similar-device isshown, except that bot-hplates'are variable in area, the uprightsupports and 51 carrying shouldered spindles 52-and 53 having heads54'and 55 cross shaped and arrangedins't aggered relation in dielectricelements 56 and 57, to avoid 'capacity'efiect.

Tliesei elements having between them a 'mica plat-e58, presentspaces-59'and 60, the

latter beingsealed', as'at 61, byT shaped inserts such'as asphaltum'orpitch and have,

in their inner adjacent sides, chambers 62 and 63 containing mercury, asat 64 and 65, the same being entered through openings 66 and 67'eventually plugged by screws 68 and 69.

\Vhen the condenser is connected in an electrical circuit it will beapparent that when the device is partially rotated, causing the mercuryto flow into the spaces 59 and 60, induction will take place through theplate 58 in the manner before described.

The foregoing disclosure is to be.regarded as descriptive andillustrative only, and not as restrictive or limitati've of theinvention, of which obviouslyan' embodiment may be constructed includingmany modifications withoutdeparting from the general scope hereinindicated and denoted in the appended claims.

An instance of another embodimentwhich I have discovered \vorksvery Wellis one in which the area-of theinercury conductors or plates may bechangedlto vary'the-capacity of the condenser by varying the space ordistance between the dielectric and the casing thus raising thelevel'of'the mercury in its chambers and in that way eliminating thereservoir; i

Having thus described myinventiomwhat I claim as new and; desire to'secure by Letters Paten't,is:'" E i 1. A variable condenser, comprisingliquid condenserplates of variable area, separated by a dielectricplate, said condenser plates mounted in =die1ecric containers,said'dielectric plate and containersfsec'ured to each other, and shaftsplaced in tandem relation formingelec'tri'calj conductors 'from each ofthe condenser plates. v 1

In a variable condenser, a dielectric base, supports securedt her'to,shafts intande'in' relation jo'i'irnal'ecb in said" supports, adielectric plate secu'red' to'ea'ch of said shafts, one of said platesformed with a flange to overlie the other and having a crescent shapedWe'll 'form'edi'n it,"both' of said plates recessed" for'hoiising"-"eii' 1arged portions on said shafts, enlarged substantiallycircular recesses in each of said plates 'a thin dielect'ric' platesecured'be'tween the first mentioned plates, and variable "Imercurycondenser plates in thespaces' formed between said three dielectricplatesQ v Signed 'at New York, in the county of New York and State-o'f-New York, this 6th day of October, A. D. 1923.

ALBERT FRANKLIN,

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